1. Field of the Invention
The present invention relates to a belt-driven recording tape cartridge and a roller therefor.
2. Description of the Related Art
Belt-driven recording tape cartridges are widely used because of their convenience and large storage capacities. They are used in, for example, computers in order to record and retrieve data.
Belt-driven recording tape cartridges are disclosed in U.S. Pat. No. 3,692,255 (hereinafter referred to as the "'255 patent"), entitled "Belt Driven Tape Cartridge"; U.S. Pat. No. 4,466,564 (hereinafter referred to as the "'564 patent"), entitled "Belt For Belt-Driven Recording Tape Pack"; U.S. Pat. No. 4,581,189 (hereinafter referred to as the "'189 patent"), entitled "Method Of Making A Belt For Belt-Driven Recording Tape Pack"; and Japanese Unexamined Patent Publication (Kokai) 8-63,936 (hereinafter referred to as the "'936 publication"), entitled "Tape Cartridge." The contents of these applications are incorporated herein by reference in their entirety.
In the tape cartridges disclosed in the '255 patent, the '564 patent, and the '189 patent, a tape cartridge has first and second tape reels. Each of the first and second tape reels is rotatable around respective axis. A magnetic recording tape is wound around the first and second tape reels to form first and second tape packs. A driving belt is in contact with the magnetic recording tape at both the first and second tape packs. Accordingly, the driving belt moves the recording tape through friction between the driving belt and the recording tape.
In this tape cartridge, stabilizing contact between the magnetic recording tape and the magnetic head of a drive improves the reliability of the tape cartridge.
In the tape cartridge disclosed in the '936 publication, a base plate and a cover surround first and second tape reels, a magnetic recording tape, a driving belt and rollers which guide the driving belt. Rough surfaces are formed at portions of the cover and/or the base plate which contact roller end surfaces which are perpendicular to axes of the rollers. The rough surfaces include many concave and convex portions. Accordingly, in this tape cartridge, a lubricant is retained in the concave portions. However, a problem arises in that a torque for rotating the roller is not stabilized, because the convex portions break the thin layer of the lubricant formed on the cover and/or the base plate. Therefore, the tape tension of the magnetic recording tape cannot be stabilized.